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Silent sting - Page 2

The US Supreme Court ruled in 1979 that the use of a pen register is "not a search under the Fourth Amendment," Susan Freiwald, a law professor at the University of San Francisco, told us. That means law-enforcement agents don't need a full-scale search warrant. And court orders permitting pen-register wiretaps are "really easy to get," Friewald explained.

To secure a judge's blessing, law enforcement agents need only to submit complete applications and show that the phone numbers dialed are "relevant" to an investigation.

Kane's email, dated in 2011, is significant because it suggests that "many agents" were using Stingrays for investigations after clearing only the low hurdle of court approval for a pen register. "The federal government was routinely using Stingray technology in the field, but failing to make that explicit in its applications to the court to engage in electronic surveillance," ACLU Staff Attorney Linda Lye wrote in a recent blog post. "When the magistrate judges in the Northern District of California finally found out what was happening, they expressed 'collective concerns,' according to the emails."

The revelation is closely tied to an electronic surveillance case that's currently making its way through court, most recently prompting the ACLU and the Electronic Frontier Foundation to file an amicus brief challenging the constitutionality of a Stingray use.

TRACKING A HACKER

It all began back in 2008, when FBI agents used the technology to track down a hacker and alleged fraudster named Daniel David Rigmaiden — a guy who sometimes goes by an alias, represented himself in court, and seems to possess enough technical savvy and disposable income to challenge his prosecutors at every turn.

Through discovery proceedings, Rigmaiden "managed to get the government to admit that it has used this location tracking technology to find him," Lye noted. "That is quite extraordinary, because there have been suspicions that that this device has been around and in use for quite a long time, but there are really very few cases where we talk about it, and this is the only criminal case where the government has plainly admitted to using it to locate a suspect."

Because FBI agents used a Stingray to locate Rigmaiden, they not only figured out that he was inside a Santa Clara apartment building, but successfully sniffed down to the level of his exact unit.

But the request for court orders that authorized this investigation made only a fleeting mention of a mobile tracking device, without conveying just how powerful the surveillance tool actually is. "When we read the orders, we were very, very surprised and troubled," Lye said. "Because the government was arguing in the criminal proceeding in Rigmaiden, yes, we acknowledge that we've used this cell site emulator, and we're even ... acknowledging that the device is intrusive enough in the way it operates to constitute a search — which is a significant concession."

In this case, the FBI agents obtained a court order to use a pen register, and separately obtained court approval to solicit Verizon's help in locating Rigmaiden, which the government claims constituted a warrant (though this is a point of contention). But nowhere did agents make it clear to the judge that in order to work, this surveillance device vacuums up vast amounts of third-party data. The search potentially affected hundreds of subscribers in Rigmaiden's apartment complex, none of whom were suspected of any involvement in wrongdoing. The government noted in court filings that it purged the third-party data after the fact, presumably as a way to deflect privacy concerns.